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TROPICAL STORM OLIVIA DISCUSSION NUMBER 7
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT TUE OCT 03 2000
AN SSM/I OVERPASS AT 1523Z SUGGESTED A FORMATIVE EYE...AND IT TRIED
TO BRIEFLY APPEAR IN VISIBLE IMAGERY JUST BEFORE SUNDOWN. THESE
SUGGEST THAT OLIVIA CONTINUES TO BECOME BETTER ORGANIZED. SATELLITE
INTENSITY ESTIMATES ARE 55 KT...55 KT...AND 45 KT FROM TAFB...SAB...
AND AFWA...SO THE MAXIMUM INTENSITY REMAINS 55 KT.
WATER VAPOR IMAGERY INDICATES A LARGE MID/UPPER LEVEL TROUGH WITH
MULTIPLE SHORTWAVES NORTH OF 20N WEST OF 115W...AND WEAK RIDGING
JUST NORTH OF OLIVIA. LARGE-SCALE MODELS INDICATE THE RIDGE WILL
BUILD WESTWARD WITH TIME...WHICH SHOULD CONTINUE A GENERAL WEST TO
WEST-NORTHWEST MOTION THROUGH THE FORECAST PERIOD. NHC TRACK
GUIDANCE GENERALLY AGREES WITH THIS SCENARIO...ALTHOUGH THERE IS
SOME SPREAD IN THE FORECAST FORWARD SPEED. THE OFFICIAL FORECAST
WILL CONTINUE TO CALL FOR A SLOWER MOTION...IN AGREEMENT WITH THE
CURRENT MOTION OF 280/4...THE NOGAPS...AND THE UKMET.
ALTHOUGH THERE IS STILL SOME EASTERLY SHEAR...OLIVIA SHOULD CONTINUE
TO STRENGTHEN FOR THE NEXT 24 HR OR SO AS IT HAS DONE TODAY. AFTER
THAT...THERE IS A POSSIBILITY THAT EASTERLY SHEAR WILL INCREASE AND
EITHER STOP INTENSIFICATION OF PERHAPS WEAKEN THE STORM. THE
INTENSITY FORECAST WILL LEVEL OFF THE INTENSIFICATION AFTER 36 HR.
IT IS NOTABLE THAT THE NOGAPS FORECAST LESS SHEAR THAN THE AVN...
AND OLIVIA COULD STRENGTHEN MORE THAN CURRENTLY FORECAST IF IT
VERIFIES.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 04/0300Z 15.6N 105.0W 55 KTS
12HR VT 04/1200Z 15.7N 105.5W 65 KTS
24HR VT 05/0000Z 15.9N 106.5W 75 KTS
36HR VT 05/1200Z 16.2N 107.5W 80 KTS
48HR VT 06/0000Z 16.5N 108.5W 80 KTS
72HR VT 07/0000Z 17.0N 110.5W 80 KTS
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